Jerry Fix asked about an "inexpensive and simple way to control power line harmonics (IEC 555 type) for medium power (500 -1000W) linear power supplies?"
Other contributors to this listserver have already pointed out that linear power supplies have exactly the same input current waveform as switching-mode power supplies. Unfortunately, TC77A, the author of EN 61000-3-2 (formerly IEC 555) has effectively outlawed the conventional (linear) power supply through the harmonic current limits published in EN 61000-3-2. The authors wrote the harmonic requirements rather deliberately to outlaw linear power supplies. They did so without notifying the folks who design products using linear power supplies! I'm frankly surprised the users of linears have not spoken their objections to TC 77A. For linear power supplies in the 75-200 watt range, sometimes a series choke can enable the supply to squeek by the limits. But not always, and never for higher power linears. I'm afraid Jerry is facing a very expensive power supply replacement. Richard Nute +=====================================================================+ |Richard Nute |Quality Department | |Hewlett-Packard Company |Product Regulations Group | |Barcelona Division (BCD) |Phone : +34 3 582 2820 | |Postal: Avinguda Graells, 501 |FAX : +34 3 582 2515 | | 08190 Sant Cugat del Valles |e-mail: [email protected] | | Barcelona, Spain | | +=====================================================================+
